Terrible customer service

Using The Courier Guy for many years but wee are having issues with overcharging and finding it impossible to get resolved. We fund ther account daily when necessary. A specific parcel which was booked at about R600.00 from JHB to Gordon's Bay tuned out that we were billed R1800 as The Courier Guy claimed that it was a weight of 172KG (Parcel was 17.5Kg). Tried to explain that a single driver cannot collect a single parcel of 172KG but they claim it is correct. Does not make logical sense and since we need to courier parcels daily, we landed up paying in so that we were not in debit. Awaiting the CT branch to measure and weigh and hopefully get a refund. The receiver was also told that our account is in debit and they cannot deliver until rectified. Disgusting customer service. We spend around 6-7k a month with them